Each Jewish New Year brings the recital of a centuries-old prayer that says: on Rosh Hashana, it is written who shall live and who shall die; who shall see ripe old age and who shall not; who shall perish by fire and who by water. Repentance, prayer and charity can avert, or temper, judgment's severe decree, the prayer concludes.

It can seem a harsh message under the best of circumstances. But several rabbis in New York said yesterday that thinking of reciting it was almost unbearable while more than 5,000 people -- including some of their own congregants -- were missing and most likely dead.

''A lot of us are thinking, 'How are we going to say that?' '' said Abby Sosland, a rabbi at the Town and Village Synagogue on East 14th Street, as she prepared for Rosh Hashana, which began last night.

As rabbis readied for an expected crush of worshipers and took steps to provide them protection and peace of mind, they also struggled for words to console and explain.

Long-planned sermons were scrapped. ''Up until last week a lot of rabbis were going to be talking about Israel, the terror it faces, the lack of hope there,'' said Rabbi Daniel Alder of the Brotherhood Synagogue in Gramercy Park. ''This has overtaken it in the lives of Americans, including American Jews.''

If anything, several rabbis said, their congregations now understand much better the fear Israelis live with. And they said the security measures taken for the High Holy Days were a preview of what life in America might become.

Many synagogues have hired extra security guards and have worked with auxiliary police officers and local precincts for heightened protection. Some said they would search bags and ask for photo identification. B'nai Jeshurun, on the Upper West Side, asked members not to bring bags to services at all, and warned that it would search even bags containing prayer shawls.

But last night, Jews throughout the region went to services, often saying that last week's attack had deepened their resolve, and need, to attend. Scott Claster, a 45-year-old actor, said he had not been inside a temple in 20 years. Last night he walked up to the building where B'nai Jeshurun was holding services and said to an usher: ''I don't have a ticket. I'm not a member of a synagogue. I just want to observe.''

Rabbis said that because people had been visiting synagogues in extraordinarily high numbers in recent days, they had scrambled to find additional space for the holidays. The Town and Village Synagogue also had to find space for members of the new Downtown Synagogue, which had planned to hold its first High Holy Day services this year near the twin towers.

At the Metropolitan Pavilion, which housed the first night services for Congregation Beth Simchat Torah, the New York-based gay synagogue, people were literally sitting on the floor. When the rabbi, Sharon Kleinbaum, asked people who had friends or relatives missing to stand for a prayer for the ill, about one fourth of the audience of 2,000 people rose to their feet.

Not surprisingly, then, rabbis struggled with how best to provide spiritual guidance. Rabbi Sosland said her first sermon would address her unease at having to say the traditional prayer about who will live and who will die.

''The biggest problem with this prayer is that so many of us read it literally, simply as a prescription for how to 'avoid death,' '' she wrote in a draft. '' 'If only we abide by the rules, we'll be fine.' I don't believe that. I can't believe that. Especially not after a week like the one we've had. Don't tell me that all those people still missing from the World Trade Center weren't living good lives. I know one of them, and I know that not to be true.''

A synagogue board member is missing.

She tried to explain that the prayer taught that human beings were not in control of their fates, but that good deeds could help make it easier to get through ''whatever the world throws at us.''

Her second sermon, she said, would talk about what Isaac did first after avoiding being sacrificed by his father: he fell in love. ''What a strong and life-affirming move,'' sh wrote. ''What a powerful response to the trauma he had gone through. Understandably, we want to run away now, we want to run to food, to substance abuse, to sleep. But we must take the lesson of Rosh Hashana and let ourselves be reborn, let ourselves love, let ourselves enter into the New Year with hope, strength and the spirit of renewal.''